Display control device, display, display system and computer-readable medium

ABSTRACT

A display control device includes a position specifying unit, an image specifying unit and a controller. The position specifying unit specifies a position of a second apparatus on a display screen of a first apparatus. The image specifying unit specifies one of an image displayed on a display screen of the second apparatus and an image that is designated from among two or more images displayed on the display screen of the second apparatus. The controller controls such that a certain image according to the image specified by the image specifying unit is displayed at a certain position on the display screen of the first apparatus according to the position of the second apparatus specified by the position specifying unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 U.S.C. §119from Japanese Patent Application No. 2007-86656 filed Mar. 29, 2007.

BACKGROUND Technical Field

The invention relates to a display control device, a display, a displaysystem, and a computer-readable medium.

SUMMARY

According to an aspect of the invention, a display control deviceincludes a position specifying unit, an image specifying unit and acontroller. The position specifying unit specifies a position of asecond apparatus on a display screen of a first apparatus. The imagespecifying unit specifies one of an image displayed on a display screenof the second apparatus and an image that is designated from among twoor more images displayed on the display screen of the second apparatus.The controller controls such that a certain image according to the imagespecified by the image specifying unit is displayed at a certainposition on the display screen of the first apparatus according to theposition of the second apparatus specified by the position specifyingunit.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention will be described in detail belowwith reference to the accompanying drawings, wherein:

FIG. 1 is a drawing to show a first example of a horizontal display anda portable display to which an exemplary embodiment of the invention isapplied;

FIG. 2 is a drawing to show an example of a code image used in the firstexample;

FIG. 3 is a drawing to show a second example of a horizontal display anda portable display to which the exemplary embodiment of the invention isapplied;

FIG. 4 is a drawing to show an example of a code image used in thesecond example;

FIG. 5 is a drawing to show a third example of a horizontal display anda portable display to which the exemplary embodiment of the invention isapplied;

FIG. 6 is a drawing to show the configuration of a wireless sensor usedin the third example;

FIG. 7 is a drawing to show a first example of display implemented inthe exemplary embodiment of the invention;

FIG. 8 is a drawing to show a second example of display implemented inthe exemplary embodiment of the invention;

FIG. 9 is a drawing to show a first configuration example of a displaysystem in the exemplary embodiment of the invention;

FIG. 10 is a drawing to show a second configuration example of thedisplay system in the exemplary embodiment of the invention;

FIG. 11 is a flowchart to show a first operation example of the displaysystem in the exemplary embodiment of the invention;

FIG. 12 is a drawing to show management information used in the firstoperation example;

FIG. 13 is a flowchart to show a second operation example of the displaysystem in the exemplary embodiment of the invention;

FIG. 14 is a drawing to show management information used in the secondoperation example; and

FIG. 15 is a diagram to show the hardware configuration of a computerthat can implement the exemplary embodiment of the invention.

DETAILED DESCRIPTION

The exemplary embodiment(s) of the invention will be described in detailwith reference to the accompanying drawings.

In the exemplary embodiment, a horizontal display for plural users tohave a discussion with gathering about the display is used as an exampleof a display. A portable display carried in by one user is placed on thehorizontal display and an electronic document displayed on the portabledisplay is shared on a shared screen on the horizontal display, tothereby have a discussion. Then, first the mechanisms of the horizontaldisplay and the portable display will be described.

To begin with, a first example of the mechanisms of the horizontaldisplay and the portable display will be described.

FIG. 1 is a section view when a portable display 20 is placed on ahorizontal display 10 in the first example. Usually, the portabledisplay 20 is in contact with the horizontal display 10, but a gap isprovided between the horizontal display 10 and the portable display 20in the figure for ease to view.

As shown in the figure, the horizontal display 10 includes a top plate11 as a workbench for having a discussion, and leg portions 12 a to 12 dfor supporting the top plate 11. The horizontal display 10 also includesa projection unit 13 for projecting an image onto the top plate 11 fromits rear, casters 14 a to 14 d for movably supporting the projectionunit 13, and a projector 15 for projecting the image to be projectedonto the top plate 11. The horizontal display 10 further includes aninfrared light source 17 for irradiating the bottom surface of theportable display 20 with infrared light and an infrared camera 18 a forreceiving the infrared light reflected on the bottom of the portabledisplay 20. However, FIG. 1 is a section view and therefore the legsportions 12 c and 12 d and the casters 14 c and 14 d do not appear inthe figure.

The top plate 11 is circular, for example, so that each user canparticipate in discussion with standing at any desired position in thesurrounding of the top plate 11. For example, a translucent white filteris put on a base material of a glass plate, etc., to form atransmission-type screen so that the top plate 11 functions as a displayscreen (for example, large screen display) for displaying an imageprojected by the projection unit 13. That is, in the exemplaryembodiment, the top plate 11 is used as an example of a display unit.Further, the top plate 11 also includes a function of a touch panel fordetecting user's operation on the displayed image. The touch panel maybe provided by covering the surface of the top plate 11 with atransparent screen where elements for detecting contact are placed ormay be provided by running infrared light vertically and horizontally onthe surface of the top plate 11 and detecting a position where theinfrared is blocked. In the exemplary embodiment, however, the portabledisplay 20 may be placed on the top plate 11 as shown in the figure.Therefore, it is assumed that the function of the touch panel of the topplate 11 is a function of discriminating between touch with the bottomsurface of the portable display 20 and touch as user's operation, forprocessing. For example, if the touch part exceeds a given area, asignal representing user's operation may be suppressed.

The number of the legs (12 a to 12 d) is four by way of example, but isnot limited to four.

The projection unit 13 is formed of a square pole box with a sidesurface of the top plate 11 being open and contains mirrors 13 a and 13b therein. It is assumed that the mirrors 13 a and 13 b are fixed atangles as shown in the figure and are attached to side surfaces of thebox of the projection unit 13.

The casters 14 a to 14 d are attached to the bottom surface of theprojection unit 13 so that the projection unit 13 can be moved with amove of a table made up of the top plate 11, the leg portions 12 a to 12d, and the projector 15. However, the relative position of theprojection unit 13 to the table is prevented from shifting. The numberof the casters is four, but is not limited to four.

The projector 15 is hung from the top plate 11 and is fixed and projectsan image in the direction of the mirror 13 a. Then, the image isreflected on the mirror 13 a and is projected onto the top plate 11.

The infrared light source 17 blinks in a pulse fashion insynchronization with the shutter timing of the infrared camera 18 a, forexample. Accordingly, an area of the top plate 11 where there is apossibility that the portable display 20 may be placed is irradiatedwith the infrared light on a regular basis. For example, an infrared LEDmay be used as the infrared light source 17.

The infrared camera 18 a captures an image of the bottom surface of theportable display 20, with which infrared light is irradiated, by animage sensor having sensitivity to the infrared region. The capturedimage is analyzed. Thereby, an ID and a position of the portable display20 are detected. For example, a CMOS sensor or a CCD sensor may be usedas the image sensor.

In the exemplary embodiment, an image is thus read with the infraredlight, so that video produced by visible light of the projector 15 isnot affected. To conduct further reliable projection and ID recognition,a holographic optical element for allowing any other than light at agiven angle to pass through may be used in the top plate 11.Alternatively, a method of putting a film, which is electricallychangeable between transmission and non-transmission, on the top plate11 and switching between projection and ID recognition in a short cyclemay also be adopted.

On the other hand, the portable display 20 may any so long as it is aportable-type terminal. A notebook PC is a representative example; a PDA(Personal Digital Assistant), a digital camera, a mobile telephone,etc., may be adopted. It is noted that a code image 26 a formed of acolor material (for example, toner) having an absorption region in theinfrared region is put on the bottom surface of the portable display 20so that the ID and the position of the portable display 20 are detectedusing the infrared light source 17 and the infrared camera 18 a.

FIG. 2 is a drawing to show an example of an image forming the codeimage 26 a.

First, unit patterns forming the code image 26 a will be described.

FIG. 2A shows an example of a unit pattern.

The unit pattern refers to the minimum unit of embedded information. Inthe figure, black regions and hatched regions are regions where dot canbe placed and white regions existing therebetween is regions where a dotcannot be placed. Dots are placed in the black regions of the regionswhere dot can be placed; dots are not placed in the hatched regions.That is, the figure shows an example in which a unit pattern is formedby placing dots in two positions selected from among the nine positionswhere dot can be placed. Here, the number of combinations of selectingtwo positions from among nine positions is equal to 36 (=₉C₂) andtherefore, 36 types of unit patterns exist. Among them, the four typesof unit patterns are used as synchronous patterns. The synchronouspatterns are patterns to detect image rotation and specify a relativeposition of an identification code. Particularly, since it is necessaryto detect image rotation, selected as the four types of unit patternsare patterns such that if one of the synchronous patterns is rotated 90degrees, it becomes another of the synchronous patterns are selected.The 32 types of unit patterns except the four types of unit patterns areused as information patterns representing an identification code, torepresent five-bit information.

By the way, the dots shown in FIG. 2A are dots for representinginformation and do not necessarily match a dot meaning the minimum pointforming a part of an image. In the exemplary embodiment, the dot forrepresenting information (minimum square in FIG. 2A) has a size of twodots×two dots in 600 dpi. Since the size of one dot in 600 dpi is 0.0423mm, one side of the dot for representing information (minimum square inFIG. 2A) is 84.6 μm (=0.0423 mm×2). The dot for representing informationmay be small as much as possible because the larger the dot becomes, themore conspicuous the dot becomes. However, if the dot is made too small,it cannot be printed by a printer. Then, the above-mentioned valuefalling within a range of from 50 μm to 100 μm is adopted as the size ofthe dot for representing information. However, the above-mentioned value84.6 μm is a numeric value on calculation and the size becomes about 100μm in an actually printed toner image.

Next, a code block made up of such unit patterns will be described.

FIG. 2B shows an example of layout of a code block. Here, the figureshows a code array just before replacement with a pattern image ratherthan an image. That is, a unit pattern (any of 36 types of unitpatterns) as in FIG. 2A is placed in the minimum square in FIG. 2B(which will be hereinafter referred to as “unit block”) and theresultant image is formed on a medium.

In the layout in FIG. 2B, a synchronous code is placed in one unit blockin the upper left corner of the code block. An identification code isplaced in four unit blocks to the right of the unit block in which thesynchronous code is placed and in four unit blocks below the unit blockin which the synchronous code is placed. Furthermore, the identificationcode is placed in 16 (=4×4) unit blocks surrounded by these unit blocks.

In the exemplary embodiment, the ID of the portable display 20 is codedand used as the identification code in the code image 26 a. In so doing,if the image captured by the infrared camera 18 a is analyzed, the ID ofthe portable display 20 is obtained and also it is possible to findwhich portable display 20 is placed on the horizontal display 10.

On the other hand, the position of the portable display 20 on thehorizontal display 10 is found based on the position and the size of thecode image in the image captured by the infrared camera 18 a. Forexample, if the code image exists on the upper side in the imagecaptured by the infrared camera 18 a, it can be found that the infraredlight is received from roughly above in the vertical direction. Morespecifically, it is assumed that an image is captured so that one sideof the infrared camera 18 a closer to a table surface is on an upperside of the captured image. In this case, if the portable display 20 islocated on the optical axis, the code image appears at the center of thecaptured image; if the portable display 20 is closer to the infraredcamera 18 a than the optical axis, the code image appears in the upperportion of the captured image; and if the portable display 2 is fartherfrom the infrared camera 18 a than the optical axis, the code imageappears in the lower portion of the captured image. If the code imageexists on the lower side in the image captured by the infrared camera 18a, it can be found that the infrared light is received from a directioncloser to the horizontal direction than the vertical direction. The sizeof the code image 26 a is determined in advance and is compared with thesize of the code image in the image captured by the infrared camera 18a. Thereby, a distance from the infrared camera 18 a to the code image26 a is recognized. Then, the position of the portable display 20 in athree-dimensional space is determined from the found direction anddistance

K (black containing carbon) toner and special toner are available as thetoner used to form the code image 26 a.

As the special toner, invisible toner having the maximum absorptionratio in a visible light region (400 nm to 700 nm) being 7% or less andthe absorption ratio in a near-infrared region (800 nm to 1000 nm) being30% or more is illustrated. However, “visible” and “invisible” do nothave a bearing on whether or not the toner (code image) can berecognized by human's eyes. “Visible” and “invisible” are distinguisheddepending on whether or not the code image can be recognized accordingto the presence or absence of color development property due toabsorption of a specific wavelength in the visible light region. If thetoner (code image) is hard to recognize with human's eyes although thereis some color development property due to absorption of the specificwavelength in the visible light region, it is also contained in“invisible.”

Next, a second example of the mechanisms of the horizontal display andthe portable display will be described.

FIG. 3 is a section view when a portable display 20 is placed on ahorizontal display 10 in the second example. A gap is also providedbetween the horizontal display 10 and the portable display 20 in thisfigure for ease to view.

As shown in the figure, the horizontal display 10 includes a top plate11, leg portions 12 a to 12 d, a projection unit 13 containing mirrors13 a and 13 b, casters 14 a to 14 d, and a projector 15, which aresimilar to those of the horizontal display 10 shown in FIG. 1 andtherefore will not be described again.

By the way, in FIG. 1, the horizontal display 10 reads the code imageretained by the portable display 20; whereas, in FIG. 3, the portabledisplay 20 reads a code image retained by the horizontal display 10.That is, in FIG. 3, the portable display 20 may be a notebook PC, etc.,as in FIG. 1, but includes an infrared light source 27 and an infraredcamera 28 in place of the code image 26 a. The functions of the infraredlight source 27 and the infrared camera 28 are the same as the functionsof the infrared light source 17 and the infrared camera 18 a in FIG. 1and therefore will not be described again.

On the other hand, the horizontal display 10 does not include theinfrared light source 17 or the infrared camera 18 a. Instead, a codeimage 16 formed with a color material (for example, toner) having anabsorption region in the infrared region is put on the surface of thetop plate 11 so that an ID and a position of the horizontal display 10are detected using the infrared light source 27 and the infrared camera28.

FIG. 4 is a drawing to show an example of an image, etc., forming thecode image 16.

FIG. 4A shows an example of a unit pattern forming the code image 26 a,but it is similar to that previously described with reference to FIG. 2Aand therefore will not be described again. In FIG. 2A, informationpatterns other than the synchronous pattern among the unit patterns aredescribed as those only representing an identification code. However, inFIG. 4, they represent not only the identification code, but also aposition code as described later.

Next, a code block formed of such unit patterns will be described.

FIG. 4B shows an example of layout of a code block. Here, this figureshows a code array just before it is replaced by a pattern image, ratherthan an image. That is, a unit pattern (any of 36 types of unitpatterns) as in FIG. 4A is placed in the minimum square in FIG. 4B(which will be hereinafter referred to as a “unit block”) and theresultant image is formed on a medium.

In the layout in FIG. 4B, the synchronous code is placed in one unitblock in the upper left corner of the code block. An X position code isplaced in four unit blocks to the right of the unit block in which thesynchronous code is placed. A Y position code is placed in four unitblocks below the unit block in which the synchronous code is placed.Further, an identification code is placed in 16 (=4×4) unit blockssurrounded by the unit blocks in which the position codes are placed.

In the exemplary embodiment, the ID of the horizontal display 10 iscoded as the identification code in the code image 16. The coordinatepositions on the horizontal display 10 are coded as the position codesin the code image 16. In so doing, if the image captured by the infraredcamera 28 is analyzed, the ID of the horizontal display 10 and acoordinate position on the horizontal display 10 are obtained and it ismade possible to find which position on which horizontal display 10 theportable display 20 is placed at.

As the toner used to form the code image 16, it is advisable to use atoner similar to that in FIG. 1.

Next, a third example of the mechanisms of the horizontal display andthe portable display will be described.

FIG. 5 is a section view when a portable display 20 is placed on ahorizontal display 10 in the third example. A gap is also providedbetween the horizontal display 10 and the portable display 20 in thefigure for ease to view.

As shown in the figure, the horizontal display 10 includes a top plate11, leg portions 12 a to 12 d, a projection unit 13 containing mirrors13 a and 13 b, casters 14 a to 14 d, and a projector 15, which aresimilar to those of the horizontal display 10 shown in FIGS. 1 and 3 andtherefore will not be described again.

By the way, in FIG. 1, the horizontal display 10 reads the informationretained by the portable display 20 using infrared light. In FIG. 5, thehorizontal display 10 reads the information retained by the portabledisplay 20 by conducting wireless communications. That is, in FIG. 5,the portable display 20 may be a notebook PC, etc., as in FIG. 1, butincludes a wireless sensor 26 b in place of the code image 26 a. On theother hand, the horizontal display 10 includes a transceiver 18 b inplace of the infrared light source 17 and the infrared camera 18 a.

The wireless sensor 26 b will be described.

FIG. 6 is a drawing to show the configuration of the wireless sensor 26b. The wireless sensor 26 b includes: a dielectric thin film 61 formed,via an oxide film on a substrate made of Si for propagating a surfaceacoustic wave (SAW); and comb-shaped electrodes (IDT: Inter-digitalTransducer) 62 a and 62 b formed on the dielectric thin film 61 forconverting an electric signal into a surface acoustic wave andconverting a surface acoustic wave into an electric signal. The wirelesssensor 26 b also includes: antennas 64 a and 64 b connected to thecomb-shaped electrodes 62 a and 62 b through impedance matching parts 63a and 63 b, respectively, for transferring a radio wave signal to andfrom the transceiver 18 b; and grounds 65 a and 65 b connected to theother of the comb-shaped electrode 62 a and 62 b.

The comb-shaped electrode 62 a and 62 b, the antennas 64 a and 64 b, andthe impedance matching parts 63 a and 63 b are formed of a conductivepattern in an integrated fashion. A material of the conductive patternmetal selected from Ti, Cr, Cu, W, Ni, Ta, Ga, In, Al, Pb, Pt, Au, Ag,etc., or any of an alloy of Ti—Al, Al—Cu, Ti—N, Ni—Cr, etc., may bedeposited as a single layer or a multilayer structure of two or morelayers. Particularly, Au, Ti, W, Al, and Cu is preferable as metal.Also, the film thickness of the metal layer may be 1 nm or more and lessthan 10 μm.

The plural wireless sensors 26 b thus configured are provided. Each ofthe wireless sensors 26 b holds the ID of a corresponding portabledisplay 20. The wireless sensors 26 b use the same frequency inprinciple. However, in order to obtain different IDs with the samefrequency, distance dimension d between the comb-shaped electrode 62 aand 62 b the wireless sensors 26 b may be made different from each otherto change a moving time of a surface acoustic wave between thecomb-shaped electrode 62 a and 62 b. Since the moving time of a surfaceacoustic wave moving on the dielectric thin film 61 is very large ascompared with the moving time of a radio wave signal between thetransceiver 18 b and the wireless sensor 26 b, the ID is set inaccordance with a propagation time t of a surface acoustic wave betweenthe comb-shaped electrode 62 a and 62 b. It is advisable to previouslystore an ID setting table that associates the propagation times t andthe IDs with each other, in storage (not shown) of the horizontaldisplay 10, for example.

The basic operation of detecting an ID using the wireless sensor 26 b isas follows:

First, the transceiver 18 b transmits a sensor question signal having afrequency of 300 MHz. Upon reception of the sensor question signal, thewireless sensor 26 b causes the dielectric thin film 61 to generate asurface acoustic wave and transmits a sensor answer signal. Then, thetransceiver 18 b receives the sensor answer signal, conducts an analysisprocess, and references the ID setting table based on the propagationtime t calculated in the analysis process to read the ID.

On the other hand, the horizontal display 10 finds a distance to theportable display 20 based on an intensity of the radio wave received bythe transceiver 18 b from the wireless sensor 26 b and calculates aposition of the portable display 20 based on the distance. If pluraltransceivers 18 b are provided, the position accuracy in thethree-dimensional space is enhanced.

In the exemplary embodiment, the horizontal display 10 is used as anexample of a display having a substantially horizontal display screen.It is assumed that the expression “substantially horizontal” does notrequire that the top plate 11 be completely parallel to the ground orfloor face and may be horizontal to such an extent that the portabledisplay 20 does not fall if the portable display 20 is placed on the topplate 11. Hereinafter, the case where the exemplary embodiment isapplied to the horizontal display 10 will be described, but theexemplary embodiment may be applied to a display of any other type suchas a vertical display.

In the exemplary embodiment, display as shown in FIGS. 7 and 8 isimplemented using the horizontal display 10 described above. Here, ascene is assumed where participants in a conference carry theirrespective portable displays 20 into a conference room to have aconference while referencing a shared screen implemented on thehorizontal display 10.

FIG. 7 is a drawing to show a first example of displaying an electronicdocument, which is displayed on the portable display 20, on thehorizontal display 10.

First, each participant places the portable display 20 on the horizontaldisplay 10 and connects the portable display 20 to a predetermined linein the conference room, for example. Then, an area corresponding to theshared screen (shared area 21 a) is displayed on a display screen 21 ofthe portable display 20 as shown in FIG. 7A. In the figure, the sharedarea 21 a is shown as an area having a given area (shaded area) on thedisplay screen 21, but may be a folder or the like, for example. On theother hand, any area other than the shared area 21 a is a personaldisplay area (personal area 21 b) and an image of an electronic documentnot shared at this time is displayed.

Next, the participant selects an image (one of images) of the electronicdocument displayed in the personal area 21 b and moves it to the sharedarea 21 a by a dragging operation, for example. Then, display on thehorizontal display 10 and that on the portable display 20 becomes asshown in FIG. 7B. That is, the moved electronic document is displayed inthe shared area 21 a and the electronic document is called from aserver, etc., and is displayed beside the portable display 20, forexample, on the horizontal display 10.

In this example, the upper side of the image of the electronic documentis displayed so as to become an opposite side to an operator of theportable display 20. Here, the upper side of the image refers to anupper side in the case where the image is placed in a predeterminedorientation that is determined as a unique attribute to the image. Thenatural orientation when a human sees an image, for example, if theimage contains text, an orientation in which a human can read the textmay be adopted as the predetermined orientation as the unique attributeto the image. In so doing, if the upper side of the image becomes theopposite side to the operator of the portable display 20, it means thatthe image is displayed in the orientation easy to see for the operatorof the portable display 20 on the horizontal display 10. However, as amethod for displaying the image of the electronic document, any otherdisplay method may be adopted. For example, a scene is also possiblewhere the participant who operates the portable display 20 explainswhile referencing the display screen 21 of the portable display 20 andany other participant receives the explanation while referencing thedisplay on the horizontal display 10. In such a case, it is desirablethat the image should be displayed in the orientation easy to see forthe participators other than the operator of the portable display 20.That is, the image of the electronic document may be displayed in astate where the upper side of the image is oriented to a direction alongwhich the display screen of the display screen 21 of the portabledisplay 20 is usually viewed.

FIG. 8 is a drawing to show a second example of displaying an electronicdocument displayed on the portable display 20 on the horizontal display10.

First, each participant places the portable display 20 on the horizontaldisplay 10. At this time, it is assumed that a third page of anelectronic document is displayed on the display screen 21 of theportable display 20. Then, on the horizontal display 10, a second pageof the electronic document is displayed to the left of the portabledisplay 20 and a fourth page of the electronic document is displayed tothe right of the portable display 20 as shown in FIG. 8A.

Next, whenever the participant performs operation of turning a page ofthe electronic document, information is transmitted to the horizontaldisplay 10 and the display is updated. For example, if the fourth pageof the electronic document is displayed on the portable display 20, theleft image is updated to the third page and the right image is updatedto a fifth page as shown in FIG. 8B.

Next, the configuration of a display system for implementing suchschematic operation will be described.

The display system of the exemplary embodiment includes (i) the casewhere the horizontal display 10 recognizes the ID of the portabledisplay 20 and the position of the portable display 20 on the horizontaldisplay 10 as shown in FIGS. 1 and 5 and (ii) the case where theportable display 20 recognizes the ID of the horizontal display 10 andthe position of the portable display 20 on the horizontal display 10 asshown in FIG. 3.

Then, the former case will be described as a first configuration exampleof the display system, and the latter case will be described as a secondexample of the display system.

FIG. 9 is a drawing to show the first configuration example.

As shown in the figure, the first configuration example of the displaysystem of the exemplary embodiment includes the horizontal display 10,the portable display 20, and a shared screen controller 30 forcontrolling the shared screen on the horizontal display 10 in accordancewith information received from the portable display 20. If thehorizontal display 10 includes the infrared light source 17 forirradiating with infrared light and the infrared camera 18 a forreceiving the infrared light reflected on the bottom surface of theportable display 20 as shown in FIG. 1, the code image 26 a is put onthe portable display 20. If the horizontal display 10 includes thetransceiver 18 b for conducting wireless communications as shown in FIG.5, the wireless sensor 26 b is attached to the portable display 20. Thehorizontal display 10 and the shared screen controller 30, and theportable display 20 and the shared screen controller 30 are connected bya LAN, for example. In the figure, one horizontal display 10 and oneportable display 20 are connected to one shared screen controller 30,but plural horizontal displays 10 and plural portable displays may beconnected to the shared screen controller 30.

In the exemplary embodiment, the horizontal display 10 is used as anexample of a first apparatus and an example of a first display, and thetop plate 11 (see FIGS. 1 and 5) is used as an example of a displayscreen of the first apparatus and an example of a first display screen.The portable display 20 is used as an example of a second apparatus andan example of a second display, and the display screen 21 (see FIGS. 7and 8) is used as an example of a display screen of the second apparatusand an example of a second display screen. Further, the shared screencontroller 30 is used as an example of a display control device and anexample of a controller.

The internal functional configurations of the respective apparatus andunits will be described.

The horizontal display 10 includes a display section 111 for performingan image display process, an ID detection section 181 for detecting theID of the portable display 20 (which will be hereinafter referred to asa “portable ID”), a position calculation section 182 for calculating aposition of the portable display 20 on the top plate 11 (which will behereinafter referred to as a “portable position”), and a communicationsection 19 for transmitting and receiving information to and from theshared screen controller 30.

The display section 111 outputs an image to be projected onto the topplate 11 to the projector 15 in accordance with information concerning adisplay state received by the communication section 19 from the sharedscreen controller 30, for example, information concerning a displayposition and a display direction (orientation).

The ID detection section 181 analyzes an image captured by the infraredcamera 18 a or the information received by the transceiver 18 b, therebydetecting the portable ID.

The position calculation section 182 analyzes the image captured by theinfrared camera 18 a or the information received by the transceiver 18b, thereby calculating the portable position.

The communication section 19 transmits an ID of the communicationsection 19, the portable ID, and the portable position to the sharedscreen controller 30 and receives an electronic document and theinformation concerning the display state in the display section 111 fromthe shared screen controller 30.

The portable display 20 includes a display section 211 for performing animage display process, an operation acceptance section 22 for acceptinga user's operation for an image, an ID retention section 261 forretaining its portable ID, and a communication section 29 fortransmitting and receiving information to and from the shared screencontroller 30.

The display section 211 performs processes for displaying an electronicdocument and changing display contents of the electronic document inresponse to the user's operation and displays an image on the displayscreen 21 (see FIGS. 7 and 8).

The operation acceptance section 22 accepts the user's operation andtransmits information concerning the user's operation to the displaysection 211 so as to produce display based on the user's operation. Theoperation acceptance section 22 also transmits the informationconcerning the user's operation to the communication section 29 so thatthe display in the horizontal display 10 is updated based on the user'soperation.

The ID retention section 261 is implemented by putting the code image 26a on the bottom surface of the portable display 20 or attaching thewireless sensor 26 b to the portable display 20. That is, in theexemplary embodiment, the code image 26 a or information retained by thewireless sensor 26 b is used as an example of information retained bythe second apparatus.

The communication section 29 transmits an ID of the communicationsection 29 and information concerning the electronic document for whichthe user's operation accepted by the operation acceptance section 22 isperformed (which will be hereinafter referred to as “documentinformation”) to the shared screen controller 30. The documentinformation mentioned here may include information for uniquelyidentifying the electronic document (which will be hereinafter referredto as a “document ID”) and page number in the electronic document.

The shared screen controller 30 includes a display state managementsection 31 for managing the display state of the horizontal display 10,a document acquisition section 32 for acquiring an electronic documentto be displayed on the horizontal display 10, and a communicationsection 39 for transmitting and receiving information to and from theportable display 20 and the horizontal display 10.

The display state management section 31 keeps track of which portabledisplay 20 is placed on which horizontal display 10. The display statemanagement section 31 also keeps track of which position the portabledisplay 20 is placed at. That is, in the exemplary embodiment, thefunction portion of the display state management section 31 is providedas an example of a position specifying unit for specifying the positionof the second apparatus. Further, the display state management section31 also keeps track of which orientation the placed portable display 20is directed toward. That is, in the exemplary embodiment, the functionportion of the display state management section 31 is provided as anexample of an orientation specifying unit for specifying the orientationof the second apparatus. Further, the display state management section31 also keeps track of an image of which electronic document isdisplayed on the display screen 21 of the portable display 20 (see FIGS.7 and 8) and how the image has been changed. That is, in the exemplaryembodiment, the function portion of the display state management section31 is provided as an example of an image specifying unit for specifyingthe image and a recognition unit for recognizing change in the image.

If there is a request for newly displaying an electronic document or apage on the horizontal display 10, the document acquisition section 32reads the electronic document or the page from a document server (notshown), the portable display 20, a memory (not shown) in the sharedscreen controller 30 in which the electronic document is previouslystored, etc.

The communication section 39 receives the horizontal ID, the portableID, the portable position from the horizontal display 10 and theportable ID and document information from the portable display 20. Thecommunication section 39 also transmits the electronic document and theinformation concerning the display state to the horizontal display 10.That is, in the exemplary embodiment, the communication section 39 isprovided as an example of a controller for controlling display.

FIG. 10 is a drawing to show the second configuration example.

As shown in the figure, the second configuration example of the displaysystem of the exemplary embodiment also includes the horizontal display10, the portable display 20, and the shared screen controller 30 forcontrolling the shared screen on the horizontal display 10 in accordancewith information received from the portable display 20. If the portabledisplay 20 includes the infrared light source 27 for irradiating withinfrared light and the infrared camera 28 for receiving infrared lightreflected on the top plate 11 of the horizontal display 10 as shown inFIG. 3, the code image 16 is put on the horizontal display 10. Also inthe configuration example, the horizontal display 10 and the sharedscreen controller 30, and the portable display 20 and the shared screencontroller 30 are connected by a LAN, for example. In the figure, onehorizontal display 10 and one portable display 20 are connected to oneshared screen controller 30. However, plural horizontal displays 10 andplural portable displays 20 may be connected to the shared screencontroller 30.

In the exemplary embodiment, the horizontal display 10 is used as anexample of the first apparatus and an example of the first display, andthe top plate 11 (see FIG. 3) is used as an example of the displayscreen of the first apparatus and an example of the first displayscreen. The portable display 20 is used as an example of the secondapparatus and an example of the second display, and the display screen21 (see FIGS. 7 and 8) is used as an example of the display screen ofthe second apparatus and an example of the second display screen.Further, the shared screen controller 30 is used as an example of thedisplay control device and an example of the controller.

The internal functional configurations of the respective apparatus andunits will be described.

The horizontal display 10 includes a display section 111 for performingan image display process, an ID retention section 161 for retaining theID of the horizontal display 10 (which will be hereinafter referred toas a “horizontal ID”), and a communication section 19 for transmittingand receiving information to and from the shared screen controller 30.

The display section 111 outputs an image to be projected onto the topplate 11 to the projector 15 in accordance with information concerning adisplay state received by the communication section 19 from the sharedscreen controller 30, for example, information concerning a displayposition and a display direction (orientation).

The ID retention section 161 is implemented by putting the code image 16on the surface of the top plate 11. That is, in the exemplaryembodiment, information retained by the code image 16 is used as anexample of information retained by the first apparatus.

The communication section 19 receives an electronic document and theinformation concerning the display state of the display section 111 fromthe shared screen controller 30.

The portable display 20 includes a display section 211 for performing animage display process, an operation acceptance section 22 for acceptinga user's operation for an image, an ID detection section 281 fordetecting the horizontal ID, a position detection section 282 fordetecting a portable position that is a position of the portable display20 itself on the horizontal display 10, and a communication section 29for transmitting and receiving information to and from the shared screencontroller 30.

The display section 211 performs processes for displaying an electronicdocument and changing display contents of the electronic document inaccordance with the user's operation and displays an image on thedisplay screen 21 (see FIGS. 7 and 8).

The operation acceptance section 22 accepts the user's operation andtransmits information concerning the user's operation to the displaysection 211 so as to produce display based on the user's operation.Also, the operation acceptance section 22 transmits the informationconcerning the user's operation to the communication section 29 so thatthe display in the horizontal display 10 is updated based on the user'soperation.

The ID detection section 281 analyzes an image captured by the infraredcamera 28, thereby detecting the horizontal ID.

The position calculation section 282 analyzes the image captured by theinfrared camera 28, thereby calculating the portable position.

The communication section 29 transmits the horizontal ID, the ID of thecommunication section 29, the portable position, and documentinformation concerning the electronic document for which user'soperation accepted by the operation acceptance section 22 is performedto the shared screen controller 30.

The shared screen controller 30 includes a display state managementsection 31 for managing the display state of the horizontal display 10,a document acquisition section 32 for acquiring an electronic documentto be displayed on the horizontal display 10, and a communicationsection 39 for transmitting and receiving information to and from theportable display 20 and the horizontal display 10.

The display state management section 31 keeps track of which portabledisplay 20 is placed on which horizontal display 10. The display statemanagement section 31 also keeps track of which position the portabledisplay 20 is placed at. That is, in the exemplary embodiment, thefunction portion of the display state management section 31 is providedas an example of a position specifying unit for specifying a position ofthe second apparatus. Further, the display state management section 31also keeps track of which orientation the placed portable display 20 isdirected toward. That is, in the exemplary embodiment, the functionportion of the display state management section 31 is provided as anexample of an orientation specifying unit for specifying an orientationof the second apparatus. Further, the display state management section31 also keeps track of an image of which electronic document isdisplayed on the display screen 21 of the portable display 20 (see FIGS.7 and 8) and how the image has been changed. That is, in the exemplaryembodiment, the function portion of the display state management section31 is provided as an example of an image specifying unit for specifyingthe image and a recognition unit for recognizing change in the image.

If there is a request for newly displaying an electronic document orpage in the horizontal display 10, the document acquisition section 32reads the electronic document or the page from a document server (notshown), the portable display 20, a memory (not shown) in the sharedscreen controller 30 in which the electronic document is previouslystored, etc.

The communication section 39 receives the horizontal ID, the portableID, the portable position and the document information from the portabledisplay 20. The communication section 39 also transmits the electronicdocument and the information concerning the display state to thehorizontal display 10. That is, in the exemplary embodiment, thecommunication section 39 is provided as an example of a controller forcontrolling display.

In the system configurations shown in FIGS. 9 and 10, the shared screencontroller 30 is provided separately from the horizontal display 10, butmay be provided integrally with the horizontal display 10. If such aconfiguration is adopted, it is not necessary to manage the horizontalID in the management information.

Next, an operation of the display system of the exemplary embodiment iswill described below.

In FIG. 9, first in the horizontal display 10, the ID detection section181 detects the portable ID, the position calculation section 182calculates the portable position, and the communication section 19transmits these pieces of information (the portable ID and the portableposition) together with the horizontal ID to the shared screencontroller 30. In the portable display 20, the operation acceptancesection 22 accepts a user's operation and the communication section 29transmits the document information of the electronic document for whichthe user's operation is performed together with the portable ID to theshared screen controller 30.

In FIG. 10, in the portable display 20, the ID detection section 281detects the horizontal ID, the position detection section 282 detectsthe portable position, and the communication section 29 transmits thesepieces of information (the horizontal ID and the portable position)together with the portable ID to the shared screen controller 30.Similarly, in the portable display 20, the operation acceptance section22 accepts a user's operation and the communication section 29 transmitsthe document information of the electronic document for which user'soperation is performed together with the portable ID to the sharedscreen controller 30.

Accordingly, the operation of the shared screen controller 30 starts.Here, the operation for implementing the display in FIG. 7 and that inFIG. 8 will be described separately.

FIG. 11 is a flowchart to show the operation of the shared screencontroller 30 to implement the display in FIG. 7.

The shared screen controller 30, first, determines as to which thecommunication section 39 receives either information containing thehorizontal ID, the portable ID, and the portable position or informationcontaining the portable ID and the document ID (step 301).

If it is determined that the communication section 39 receives theinformation containing the horizontal ID, the portable ID and theportable position, the received information is passed to the displaystate management section 31. If the system has the configuration shownin FIG. 9, the information is received from the horizontal display 10.If the system has the configuration shown in FIG. 10, the information isreceived from the portable display 20. The display state managementsection 31 determines as to whether or not association among thehorizontal ID, the portable ID and the portable position changes (step302). If change is not detected, the process is terminated. If change isdetected, association among the received horizontal ID, the receivedportable ID, and the received portable position is registered (step303).

If it is determined that the information containing the portable ID andthe document ID is received, the received information is also passed tothe display state management section 31. In this case, the informationis received from the portable display 20 regardless of whether thesystem has the configuration shown in FIG. 9 or that shown in FIG. 10.The display state management section 31 determines as to whether or notassociation between the portable ID and the document ID changes (step304). If change is not detected, the processing is terminated. If changeis detected, association between the received portable ID and receivedthe document ID is registered (step 305).

Following step 303 if it is determined at step 302 that change isdetected or following step 305 if it is determined at step 304 thatchange is detected, the display state management section 31 calculates adisplay position and a display direction (orientation) of the electronicdocument on the horizontal display 10 (step 306). For example, in FIG.7, a position beside the portable position received at step 301 iscalculated as the display position.

The document acquisition section 32 reads the electronic document to bedisplayed (step 307). Here, it is not necessary that the electronicdocument to be displayed is the same as the electronic document forwhich the user's operation is performed in the portable display 20. Forexample, another electronic document previously associated with theelectronic document for which the user's operation is performed may beselected as the electronic document to be displayed. In this case, animage of the other electronic document previously associated is anexample of an image having a predetermined relationship. If the imagehaving the predetermined relationship is thus selected, the displayposition and the display direction (orientation) calculated at step 306may be set according to the predetermined relationship.

Then, the communication section 39 transmits information of the displayposition and the display direction (orientation) calculated at step 306and the electronic document read at step 307 to the horizontal display10 (step 308).

Accordingly, in the horizontal display 10, the image of the transmittedelectronic document is displayed at the transmitted display position inthe transmitted display direction (orientation).

Management information referenced and updated by the display statemanagement section 31 in the process shown in FIG. 11 will be described.It is advisable to previously store the management information in amemory (not shown) that can be referenced by the display statemanagement section 31.

Before the management information is described, first, coordinates on ascreen of the horizontal display 10 will be described. FIG. 12A shows anexample of the coordinates set on the screen. Here, the screen isrectangular and its center point is the origin. An X axis is taken inthe longer direction and a Y axis is taken in the shorter direction.

On the screen, positions where the portable display 20 is placed areindicated by a quadrangle having A1, B1, C1, and D1 as vertexes and aquadrangle having A2, B2, C2, and D2 as vertexes. However, this is anexample. Of points arranged like a lattice with short spacing, a pointexisting in an area where the portable display 20 is placed may bemanaged, for example.

FIG. 12B shows contents of the management information when the portabledisplays 20 are thus placed. It is assumed that FIG. 12A shows a statewhere the portable displays 20 are placed on the horizontal display 10having a horizontal ID “P001” and that the horizontal display 10 havinga horizontal ID “P002” is also managed separately from the horizontaldisplay 10 having the horizontal ID “P001.”

For the coordinates in the portable position column in FIG. 12 B, “x” issuffixed to a symbol assigned to a point in FIG. 12A, therebyrepresenting an X coordinate of that point, and “y” is suffixed to asymbol assigned to a point in FIG. 12A, thereby representing a Ycoordinate of that point. In this case, the portable display 20 isapproximated to a rectangle and a range where the portable display 20 isplaced is represented by coordinates of four vertexes. In order toindicate which orientation the portable display 20 is placed in on thescreen, coordinates of three points of an upper left point, an upperright point and a lower left point are stored. Further, document IDs ofelectronic documents, for which user's operation is performed, among theelectronic documents displayed on the portable displays 20 are alsostored in the management information.

At step 302 in FIG. 11, it is determined as to whether or notassociation among the horizontal ID, the portable ID, and the portableposition changes in the management information shown in FIG. 12B. If itis determined that change is detected, the already registeredassociation is changed to new association at step 303. At step 304 inFIG. 11, it is determined as to whether or not association between theportable ID and the document ID changes in the management informationshown in FIG. 12B. If it is determined that change is detected, thealready registered association is changed to new association at step305.

FIG. 13 is a flowchart to show the operation of the shared screencontroller 30 to implement the display in FIG. 8.

In the shared screen controller 30, first it is determined which thecommunication section 39 receives either information including thehorizontal ID, the portable ID, and the portable position or informationincluding the portable ID, the document ID, and the page number (step351).

If it is determined that the information including the horizontal ID,the portable ID, and the portable position is received, the receivedinformation is passed to the display state management section 31. If thesystem has the configuration shown in FIG. 9, the information isreceived from the horizontal display 10. If the system has theconfiguration shown in FIG. 10, the information is received from theportable display 20. The display state management section 31 determinesas to whether or not association among the horizontal ID, the portableID, and the portable position changes (step 352). If change is notdetected, the process is terminated. If change is detected, theassociation among the received horizontal ID, the received portable IDand the received portable position is registered (step 353).

If it is determined that the information including the portable ID, thedocument ID, and the page number is received, the received informationis also passed to the display state management section 31. In this case,the information is received from the portable display 20 regardless ofeither the system configuration is that shown in FIG. 9 or 10. Then, thedisplay state management section 31 determines as to whether or notassociation among the portable ID, the document ID, and the page numberchanges (step 354). If change is not detected, the process isterminated. If change is detected, the association among the receivedportable ID, the received document ID and the received page number isregistered (step 355).

Following step 353 if it is determined at step 352 that change isdetected or following step 355 if it is determined at step 354 thatchange is detected, the display state management section 31 calculatesdisplay positions and a display direction (orientation) of pagespreceding and following the page of the electronic document displayed onthe portable display 20 placed on the horizontal display 10 (step 356).For example, in FIG. 8, positions to the left and the right of theportable position received at step 351 are calculated as the displaypositions.

The document acquisition section 32 reads the pages preceding andfollowing the page displayed on the portable display 20 as pages to bedisplayed (step 357). However, it is not necessary that the pages to bedisplayed are the pages preceding and following the displayed page. Forexample, any other page previously associated with the page displayed onthe portable display 20 may be selected as the page to be displayed.Alternatively, the display control on the horizontal display 10 may beperformed in other units than the page units. For example, among imagedata in one folder, image data created just before and image datacreated just after the image data displayed on the portable display 20in the time sequence may be read as the data to be displayed. That is,in the exemplary embodiment, an image of the preceding page and an imageof the following page are used as an example of the two images precedingand following in a predetermined order relation. The positions to theleft and the right of the portable display 20 are used as an example ofthe two symmetrical positions with the position of second apparatus as acenter.

Then, the communication section 39 transmits information of the displaypositions and the display directions (orientations) calculated at step356 and the pages read at step 357 to the horizontal display 10 (step358).

Accordingly, in the horizontal display 10, the transmitted pages aredisplayed at the transmitted display positions in the transmitteddisplay direction (orientation).

Management information referenced and updated by the display statemanagement section 31 in the process shown in FIG. 13 will be described.It is advisable to previously store the management information in amemory (not shown) that can be referenced by the display statemanagement section 31.

Also in the management information, it is assumed that coordinates arerepresented in the same manner as those previously described withreference to FIG. 12A and the portable displays 20 are placed as in FIG.12A.

FIG. 14 shows contents of the management information when the portabledisplays 20 are thus placed. Here, it is assumed that the horizontaldisplay 10 having a horizontal ID “P002” is also managed separately fromthe horizontal display 10 having a horizontal ID “P001” shown in FIG.12A. Document IDs and pages of electronic documents for which a user'soperation is performed among the electronic documents displayed on theportable displays 20 are also stored in the management information.

At step 352 in FIG. 13, it is determined as to whether or not theassociation among the horizontal ID, the portable ID and the portableposition changes in the management information in FIG. 14. If it isdetermined that change is detected, the already registered associationis changed to new association at step 353. At step 354 in FIG. 13, it isdetermined as to whether or not the association among the portable ID,the document ID and the page number changes in the managementinformation in FIG. 14. If it is determined that change is detected, thealready registered association is changed to new association at step355.

Last, to implement the exemplary embodiment as a computer 90, thehardware configuration of the computer 90 will be described.

FIG. 15 is a diagram to show the hardware configuration of the computer90.

As shown in the figure, the computer 90 includes a CPU (CentralProcessing Unit) 91 of computation means and main memory 92 and amagnetic disk unit (HDD: Hard Disk Drive) 93 of storage means. The CPU91 executes various types of software of OS (Operating System),applications, etc., for implementing the functions described above. Themain memory 92 is a storage area for storing various types of software,data used for execution of the software, and the like, and the magneticdisk unit 93 is a storage area for storing input data to various typesof software, output data from various types of software, and the like.

Further, the computer 90 includes a communication I/F 94 for conductingexternal communications, a display mechanism 95 made up of video memory,a display, etc., and input devices 96 of a keyboard, a mouse, etc.

The program for implementing the exemplary embodiment can be providednot only through communication means, but also as a computer-readablerecording (storage) medium such as a CD-ROM storing the program.

The foregoing description of the exemplary embodiments of the inventionhas been provided for the purposes of illustration and description. Itis not intended to be exhaustive or to limit the invention to theprecise forms disclosed. Obviously, many modifications and variationswill be apparent to practitioners skilled in the art. The exemplaryembodiments were chosen and described in order to best explain theprinciples of the invention and its practical applications, therebyenabling others skilled in the art to understand the invention forvarious embodiments and with the various modifications as are suited tothe particular use contemplated. It is intended that the scope of theinvention be defined by the following claims and their equivalents.

FIG. 2

-   -   A. SYNCHRONOUS CODE    -   B. IDENTIFICATION CODE        FIG. 4    -   A. SYNCHRONOUS CODE    -   B. X POSITION CODE    -   C. Y POSITION CODE    -   D. IDENTIFICATION CODE        FIG. 9    -   10 HORIZONTAL DISPLAY    -   19 COMMUNICATION SECTION    -   20 PORTABLE DISPLAY    -   22 OPERATION ACCEPTANCE SECTION    -   29 COMMUNICATION SECTION    -   30 SHARED SCREEN CONTROLLER    -   31 DISPLAY STATE MANAGEMENT SECTION    -   32 DOCUMENT ACQUISITION SECTION    -   39 COMMUNICATION SECTION    -   111 DISPLAY SECTION    -   181 ID DETECTION SECTION    -   182 POSITION CALCULATION SECTION    -   211 DISPLAY SECTION    -   261 ID RETENTION SECTION    -   A. PORTABLE ID, DOCUMENT INFORMATION    -   B. HORIZONTAL ID, PORTABLE ID, PORTABLE POSITION    -   C. ELECTRONIC DOCUMENT, DISPLAY STATE        FIG. 10    -   10 HORIZONTAL DISPLAY    -   19 COMMUNICATION SECTION    -   20 PORTABLE DISPLAY    -   22 OPERATION ACCEPTANCE SECTION    -   29 COMMUNICATION SECTION    -   30 SHARED SCREEN CONTROLLER    -   31 DISPLAY STATE MANAGEMENT SECTION    -   32 DOCUMENT ACQUISITION SECTION    -   39 COMMUNICATION SECTION    -   111 DISPLAY SECTION    -   161 ID RETENTION SECTION    -   211 DISPLAY SECTION    -   281 ID DETECTION SECTION    -   282 POSITION DETECTION SECTION    -   A. PORTABLE ID, DOCUMENT INFORMATION    -   B. HORIZONTAL ID, PORTABLE ID, PORTABLE POSITION    -   C. ELECTRONIC DOCUMENT, DISPLAY STATE        FIG. 11    -   S301 WHAT IS RECEIVED INFORMATION?    -   A. HORIZONTAL ID+PORTABLE ID+PORTABLE POSITION    -   B. PORTABLE ID+DOCUMENT ID    -   S302 CHANGE?    -   S303 REGISTER HORIZONTAL ID, PORTABLE ID, AND PORTABLE POSITION    -   S304 CHANGE?    -   S305 REGISTER PORTABLE ID AND DOCUMENT ID    -   S306 CALCULATE DISPLAY POSITION AND DISPLAY DIRECTION        (ORIENTATION) OF ELECTRONIC DOCUMENT    -   S307 READ ELECTRONIC DOCUMENT    -   S308 TRANSMIT ELECTRONIC DOCUMENT AND INFORMATION OF DISPLAY        POSITION/DISPLAY DIRECTION (ORIENTATION)        FIG. 12    -   A. HORIZONTAL ID    -   B. PORTABLE ID    -   C. PORTABLE POSITION    -   D. DOCUMENT ID        FIG. 13    -   S351 WHAT IS RECEIVED INFORMATION?    -   A. HORIZONTAL ID+PORTABLE ID+PORTABLE POSITION    -   B. PORTABLE ID+DOCUMENT INFORMATION    -   S352 CHANGE?    -   S353 REGISTER HORIZONTAL ID, PORTABLE ID, AND PORTABLE POSITION    -   S354 CHANGE?    -   S355 REGISTER PORTABLE ID, DOCUMENT ID, AND PAGE NUMBER    -   S356 CALCULATE DISPLAY POSITIONS AND DISPLAY DIRECTIONS        (ORIENTATIONS) OF PRECEDING AND FOLLOWING PAGES    -   S357 READ PRECEDING AND FOLLOWING PAGES    -   S358 TRANSMIT PRECEDING AND FOLLOWING PAGES AND INFORMATION OF        DISPLAY POSITIONS AND DISPLAY DIRECTIONS (ORIENTATIONS)        FIG. 14    -   A. HORIZONTAL ID    -   B. PORTABLE ID    -   C. PORTABLE POSITION    -   D. DOCUMENT ID        FIG. 15    -   92 MAIN MEMORY    -   93 MAGNETIC DISK UNIT    -   94 COMMUNICATION I/F    -   95 DISPLAY MECHANISM    -   96 INPUT DEVICE

What is claimed is:
 1. A display control device for a first displayscreen of a first display apparatus and a second display screen of asecond display apparatus, comprising: a position specifying unit thatspecifies a position of the second display apparatus placed on the firstdisplay screen of the first display apparatus to determine the positionof the certain image displayed on the first display screen; an imagespecifying unit that specifies an image stored on the second displayapparatus and displayed on the second display screen of the seconddisplay apparatus; and a controller that controls such that a certainimage according to the image specified by the image specifying unit isdisplayed at a certain position on the first display screen of the firstdisplay apparatus, wherein the second display screen of the seconddisplay apparatus includes a shared area and a personal area, and if theimage specified by the image specifying unit and displayed in thepersonal area moves to the shared area, the certain image according tothe moved image is displayed at the certain position on the firstdisplay screen while displaying the moved image in the shared area. 2.The display control device according to claim 1, wherein the imagespecifying unit specifies the image displayed on the second displayscreen of the second display apparatus, and the certain image is thesame image as the image specified by the image specifying unit.
 3. Thedisplay control device according to claim 1, wherein the imagespecifying unit specifies the image that is designated from among two ormore images displayed on the second display screen of the second displayapparatus, and the certain image is different from the image specifiedby the image specifying unit.
 4. The display control device according toclaim 1, wherein the controller controls such that the certain image isdisplayed in a state where an upper side of the certain image isoriented to a direction along which the second display screen of thesecond display apparatus is usually viewed.
 5. The display controldevice according to claim 1, wherein the certain image is an imagehaving a predetermined first relationship with the image specified bythe image specifying unit, and the certain position is a position havinga second relationship in arrangement, according to the predeterminedfirst relationship, with the position of the second display apparatusspecified by the position specifying unit.
 6. The display control deviceaccording to claim 1, wherein the certain image includes two imagespreceding and following the image specified by the image specifying unitin a predetermined sequence relationship, and the certain positionincludes two positions that are symmetrical with the position of thesecond display apparatus specified by the position specifying unit as acenter.
 7. The display control device according to claim 1, furthercomprising: an orientation specifying unit that specifies an orientationof the second display apparatus on the first display screen of the firstdisplay apparatus, wherein the controller controls such that the certainimage is displayed in accordance with the orientation of the seconddisplay apparatus specified by the orientation specifying unit.
 8. Thedisplay control device according to claim 1, wherein the positionspecifying unit specifies the position of the second display apparatusbased on information that is acquired when the first display apparatusacquires information retained by the second display apparatus.
 9. Thedisplay control device according to claim 1, wherein the positionspecifying unit specifies the position of the second display apparatusbased on information that is acquired when the second display apparatusacquires information retained by the first display apparatus.
 10. Thedisplay control device according to claim 1, further comprising: arecognition unit that recognizes change in the image displayed on thesecond display screen of the second display apparatus, wherein thecontroller controls such that the certain image, according to an imagedisplayed on the second display screen of the second display apparatusafter the change recognized by the recognition unit is made, isdisplayed at the certain position on the first display screen of thefirst display apparatus.
 11. The display control device according toclaim 1, wherein the position specifying unit determines the positionand an identification of the second display apparatus by capturing acode image.
 12. The display control device according to claim 1, whereinthe second display screen of the second display apparatus placed on thefirst display apparatus includes a shared area and a personal area, andif an image displayed in the personal area moves to the shared area, theimage displayed in the personal area is displayed on the first displayscreen of the first display apparatus as the certain image and isdisplayed in the shared area.
 13. The display control device accordingto claim 1, wherein the certain image is displayed in a state where anupper side of the certain image is oriented in a direction parallel toan upper edge of the second display screen of the second displayapparatus.
 14. The display control device according to claim 1, whereinthe certain image displayed on the first display screen and the movedimage displayed on the second display screen have the same content. 15.The display control device according to claim 1, wherein: the positionspecifying unit specifies the position and an identification of thesecond display apparatus placed on the first display screen of the firstdisplay apparatus by capturing a tangible code image formed on a bottomsurface of the second display apparatus.